碳黑含量对放电等离子烧结Fe-Cr-C/TiCN复合材料组织和耐磨性的影响

Effect of Carbon Content on Microstructure and Wear Resistance of Fe-Cr-C/TiCN Composites by Spark Plasma Sintering

摘要:

采用机械合金化和放电等离子烧结法制备了不同碳含量的Fe-Cr-C/TiCN复合材料。通过扫描电镜、X射线衍射、维氏硬度和球-盘式摩擦试验，系统地研究了碳含量对Fe-Cr-C/TiCN复合材料组织和磨损性能的影响。结果表明，在含碳量为1.0%~5.0%（质量分数，下同）的烧结样品中形成了(Cr, Fe)₇C₃碳化物，而当碳含量达到4.0%~5.0%时，出现了(Cr, Fe)₃C相。碳含量对Fe-Cr-C/TiCN复合材料的组织均匀性和致密化有着较为重要的影响，当烧结温度为~1000 ℃时，致密度由未加碳时的95.0%提高到的99.7%（含碳量为3.0%），说明已实现了完全致密化。当含碳量为3.0%时，维氏硬度达到11 940 MPa。此外，添加适量的碳（3.0%）有助于获得良好的磨损性能，即摩擦系数波动范围小，平均摩擦系数为0.320，磨损率为6.8×10^-4 mm³·N^-1·m^-1。

Abstract:

Fe-Cr-C/TiCN composites with different carbon contents were prepared via mechanical alloying followed by spark plasma sintering. The effects of carbon black content on the microstructure and wear properties of Fe-Cr-C/TiCN composites were systematically investigated by scanning electron microscopy, X-ray diffraction, Vickers hardness test, and ball-on-disk type tribotest. The results show that the (Cr, Fe)₇C₃ carbides form in the sintered specimens with 1wt%~5wt% carbon, but (Cr, Fe)₃C phases appear when the carbon black content reaches 4wt%~5wt%. Carbon black content plays a significant role in the microstructure uniformity and densification of the Fe-Cr-C/TiCN composites. When the sintering temperature is ~1000 °C, the relative density of specimen without carbon addition increases from 95.0% to 99.7% of the specimen with carbon addition of 3wt%, indicating that the full densification is realized. High Vickers hardness of 11 940 MPa is achieved for the specimen with carbon addition of 3wt%. Furthermore, adding an appropriate amount of carbon (3wt%) contributes to the excellent wear properties with narrow fluctuation ranges of friction coefficient, suggesting an average friction coefficient of 0.320 and wear rate of 6.8×10^-4 mm³·N^-1·m^-1.